Epiphan VGA2USB Pro - Manual (Page 151)

18. Advanced topics About the frame rate
User Guide Page 151
4 Edit the Target field and add command line options after the
closing quote.
For example, to add the --topmost command line option:
"C:\Program Files\VGA2USB DVI2USB KVM2USB\v2ugui2.exe" --topmost
For example, to add --topmost and --borderless, set the
horizontal shift to -67, and the vertical shift to 10:
"C:\Program Files\VGA2USB DVI2USB KVM2USB\v2ugui2.exe" --topmost
--borderless --hs -67 --vs 10
5 Select OK to save your changes to the shortcut.
Double-click on the shortcut to start the video capture
application with the command line options.
About the frame rate
The Frame rate at which your Frame Grabber and the video
capture application operates depends on the resolution of the
VGA or DVI source on the Frame Grabber that you are using, and
on the video capture workstation hardware.
For Frame Grabbers that do not support hardware compression,
performance and frame rate is limited mostly by USB throughput.
The theoretical limit for USB 2.0 is 60 MB/sec and the practical
limit for bulk transfers is between 20 and 40 MB/sec.
The theoretical maximum frame rate can be determined using the
following calculation:
theoretical maximum frame rate= (20000000/(n*w*h))
Where:
• w and h are the number of columns and rows in the video
mode (for example, 800x600 or 1024x768).
• n is number of bytes per pixel (from 1 to 3, see below)
The real maximum frame rate is usually lower than the
theoretical maximum frame rate because the real maximum frame
rate is limited by the video capture workstation CPU and
memory or by extra load on the USB bus (for example, if you have
other USB devices on the same USB bus).